CFD Simulation of the Laboratory-Scale Anaerobic Digester to Study the Impacts of Impeller Geometric and Operational Parameters on Its Performance

2021 ◽  
Author(s):  
Mohammad Esmaeel Kashfi ◽  
Ramin Kouhikamali ◽  
Gholam Khayati ◽  
Javad Mahmoudimehr
Keyword(s):  
Cfd Simulation ◽  
Anaerobic Digester ◽  
Laboratory Scale ◽  
Operational Parameters

Thermal Destruction Behavior of Plastic and Nonplastic Wastes in a Laboratory-Scale Facility

1996 ◽  
Vol 118 (4) ◽  
pp. 269-276 ◽  
Author(s):  
A. K. Gupta ◽  
E. Ilanchezhian ◽  
E. L. Keating
Keyword(s):  
Thermal Destruction ◽  
Laboratory Scale ◽  
Operational Parameters ◽  
Feed Composition ◽  
Equilibrium Study ◽  
Toxic Emissions ◽  
Calculation Results ◽  
Computer Codes ◽  
Combustion Tests ◽  
Experimental And Theoretical Studies

Experimental and theoretical studies are presented from a laboratory-scale thermal destruction facility on the destruction behavior of surrogate plastic and nonplastic solid wastes. The nonplastic waste was cellulosic, while the plastic waste contained compounds, such as polyethylene, polyvinyl chloride, polystyrene, polypropylene, nylon, rubber, and polyurethane, or any of their desired mixtures. A series of combustion tests was performed with samples containing varying composition test was performed with samples containing varying composition of plastic and nonplastic. Experimental results are presented on combustion parameters (CO, excess air, residence time) and toxic emissions (dioxin, furan, metals). Equilibrium thermochemical calculations are presented on the thermal destruction behavior of samples under conditions of pyrolysis, combustion, and pyrolysis followed by combustion. Special interest is on the effect of waste properties and input operational parameters on chemistry and product composition. STANJAN and SOLGASMIX computer codes were used in the chemical equilibrium study. Analysis and interpretation of the data reveal the effect of waste feed composition on combustion parameters and dioxin, furan, and metals emission. Equilibrium calculation results are used to describe the experimentally observed trends for the thermal destruction behavior of these wastes. The results show significant influence of plastic on combustion characteristics, and dioxin, furan, and metals emission.

Patterns of Hydrogen in Biogas from the Anaerobic Digestion of Milk-Sugars

1989 ◽  
Vol 21 (4-5) ◽  
pp. 187-196 ◽  
Author(s):  
F. E. Mosey ◽  
X. A. Fernandes
Keyword(s):  
Anaerobic Digestion ◽  
Anaerobic Digester ◽  
Laboratory Scale ◽  
Feed Pump ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Skimmed Milk

Concentrations of hydrogen (1-1000 vpm) in the biogas from a laboratory-scale anaerobic digester, fed with (70 g/l) reconstituted skimmed milk as substrate, were intensively monitored to determine whether hydrogen could provide a useful new alarm/loading indicator for the anaerobic digestion process. With fast-fermenting substrates such as milk-sugars it proved to be a very sensitive event-marker, producing small ripples in time with operation of the digester feed pump as well as larger pulses caused by chloroform toxicity. Scavenging of hydrogen by lithotropic methanogens appeared to promote the fermentation of sugars directly to acetate, bypassing both the formation and subsequent breakdown of higher acids, a feature that is likely to prove peculiar to methanogenic and sulphate-reducing fermentations.

scholarly journals Comparison of Two Single Stage Low-Pressure Rotary Lobe Expander Geometries in Terms of Operation

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4512
Author(s):  
Michalina Kurkus-Gruszecka ◽  
Piotr Krawczyk
Keyword(s):  
Cfd Simulation ◽  
Mechanical Energy ◽  
Electric Energy ◽  
Low Pressure ◽  
Single Stage ◽  
Small Scale ◽  
Operational Parameters ◽  
Data Simulation ◽  
Time Step ◽  
Geometry Model

In the article the computational fluid dynamics (CFD) simulation and calculated operational parameters of the single stage low-pressure rotary lobe expander compared with the values obtained from a different geometry simulation are presented. Low-pressure rotary lobe expanders are rotary engines that use a compressed gas to produce mechanical energy, which in turn can be converted into another form, i.e., electric energy. Currently, expanders are used in narrow areas, but have a large potential in the energy production from gases of low thermodynamic parameters. The first geometry model was designed on the basis of an industrial device and validated with the empirical data. Simulation of the second geometry was made based on a validated model in order to estimate the operational parameters of the device. The CFD model included the transient simulation of compressible fluid in the geometry changing over time and the rotors motion around two rotation axes. The numerical model was implemented in ANSYS CFX software. After obtaining simulation results in the form of parameters monitors for each time step, a number of calculations were performed using a written code analysing the CFD program output files. The article presents the calculation results and the geometries comparison in terms of work efficiency. The research indicated that the construction of the device on a small scale could cause a significant decrease in the aforementioned parameter, caused by medium leaks in the expander clearances.

Efficient treatment of dairy processing wastewater in a laboratory scale Intermittently Aerated Sequencing Batch Reactor (IASBR)

2018 ◽  
Vol 85 (3) ◽  
pp. 379-383 ◽  
Author(s):  
Peter Leonard ◽  
Emma Tarpey ◽  
William Finnegan ◽  
Xinmin Zhan
Keyword(s):  
Wastewater Treatment ◽  
Retention Time ◽  
Wastewater Treatment Plant ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Treatment Plant ◽  
Laboratory Scale ◽  
Synthetic Wastewater ◽  
Operational Parameters ◽  
Dairy Processing

This Research Communication describes an investigation into the viability of an Intermittently Aerated Sequencing Batch Reactor (IASBR) for the treatment of dairy processing wastewater at laboratory-scale. A number of operational parameters have been varied and the effect has been monitored in order to determine optimal conditions for maximising removal efficiencies. These operational parameters include Hydraulic Retention Time (HRT), Solids Retention Time (SRT), aeration rate and cycle length. Real dairy processing wastewater and synthetic wastewater have been treated using three laboratory-scale IASBR units in a temperature controlled room. When the operational conditions were established, the units were seeded using sludge from a municipal wastewater treatment plant for the first experiment, and sludge from a dairy processing factory for the second and third experiment. In experiment three, the reactors were fed on real wastewater from the wastewater treatment plant at this dairy processing factory. These laboratory-scale systems will be used to demonstrate over time that the IASBR system is a consistent, viable option for treatment of dairy processing wastewater in this sector. In this study, the capacity of a biological system to remove both nitrogen and phosphorus within one reactor will be demonstrated. The initial operational parameters for a pilot-scale IASBR system will be derived from the results of the study.

Effect of Scale on Hydrodynamics of Internal Gas-Lift Loop Reactor-Type Anaerobic Digester Using CFD

2015 ◽  
Vol 10 (3) ◽  
pp. 179-192 ◽  
Author(s):  
Mehul S. Vesvikar ◽  
Muthanna Al-Dahhan
Keyword(s):  
Gas Flow ◽  
Draft Tube ◽  
Liquid Velocity ◽  
Anaerobic Digester ◽  
Tube Diameter ◽  
Laboratory Scale ◽  
Dead Volume ◽  
Loop Reactor ◽  
Liquid Circulation ◽  
Gas Lift

Abstract This work evaluates the ability of computational fluid dynamics (CFD) to simulate the flow and predict the hydrodynamics of internal gas-lift loop reactor (IGLR)-type anaerobic digester. In addition, it also analyzes if CFD can account for the effects of operating conditions, geometry as well as scale of the reactor. For this purpose, three-dimensional two-phase CFD simulations were performed using CFX for laboratory-scale and pilot-scale IGLR. The CFD predictions were evaluated against experimental data obtained from computer automated radioactive particle tracking (CARPT). The CFD predictions provided good qualitative but only reasonable quantitative comparison. After validation of CFD model, effect of gas flow rate, draft tube diameter, sparger geometry and reactor scale on flow pattern, liquid velocity and dead volume was investigated. Higher gas flow rates did not offer any significant advantage in increasing liquid circulation in the downcomer or decreasing the dead volume. Configuration with draft tube diameter half of tank diameter, equipped with cross sparger showed comparatively better liquid circulation than other configurations. For same superficial gas velocity, increasing the scale increases the magnitude of liquid velocity but fails to match the mixing intensity observed in laboratory scale. Different interphase forces, turbulence models and closures are also evaluated to improve the predictability of CFD models.

Influence of operational parameters on performance of twin thermoacoustic prime mover – CFD studies

2016 ◽  
Vol 33 (3) ◽  
Author(s):  
Jabbar P ◽  
Hariharan N.M ◽  
Palani Sivashanmugam ◽  
S. Kasthurirengan
Keyword(s):  
Temperature Gradient ◽  
Design Methodology ◽  
Cfd Simulation ◽  
Working Fluid ◽  
Geometrical Parameters ◽  
Pressure Amplitude ◽  
Prime Mover ◽  
Operational Parameters ◽  
Fluid Medium ◽  
Wide Range

Purpose The present investigation deals with the analysis of the performance of twin thermoacoustic prime mover (TAPM) which are measured in terms of frequency and pressure amplitude by varying the parameters such as temperature gradient along the length of stack and the operating pressures of fluid medium argon using CFD simulation. With the help of CFD researchers and Engineers can evaluate the performance of a wide range of thermoacoustic systems on the computer without the time, expense, and disruption required to make actual changes onsite (stack) which is tedious to fabricate. Design/methodology/approach For the present simulation, the operating pressures of argon such as 1bar, 3bar and 5bar, and the temperature gradient is varied from 600K to 1400K with the regular intervals of each 200K. The geometry of twin TAPM is created using GAMBIT processor, and the simulation is carried out using FLUENT. The geometrical parameters of twin TAPM are kept constant throughout the simulation. The results for frequency and pressure amplitude obtained from the CFD simulation of twin TAPM for various temperature gradient and operating pressures are analysed and reported. Findings The computational results of twin thermoacoustic prime mover shows an increase in pressure amplitude with an increase in the temperature gradient and also it increases with an increase in operating pressures of the fluid medium. The parameter operating pressures of the working fluid medium and the stack hot end temperature has no significant effect on the output, frequency. Originality/value Though several experimental works had been published based on the twin thermoacoustic prime mover, an attempt has been made in the present investigation for the first time to estimate the performance of twin thermoacoustic prime mover using CFD package (ANSYS-FLUENT) by varying temperature gradient. The temperature gradient and operating pressures were varied and the performance of twin thermoacoustic prime mover was measured in terms of frequency and pressure amplitude.

scholarly journals Designing of lab-scale anaerobic digester equipped with maxblend impeller to evaluate effect of mixing on anaerobic digestion

2019 ◽  
Vol 4 (1) ◽  
pp. 404-413
Author(s):  
Singh Buta ◽  
Zoltán Szamosi ◽  
Zoltán Siménfalvi
Keyword(s):  
Anaerobic Digestion ◽  
Anaerobic Digester ◽  
Gas Composition ◽  
Operational Parameters ◽  
Biogas Yield ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Mixing Intensity ◽  
Enhance Efficiency ◽  
Gas Volume

Operational parameters can be easily controlled at lab scale experiments for an anaerobic digestion process. Our aim is to design a lab-scale digester equipped with an impeller to investigate how the geometry of impeller and different mixing modes effect the biogas yield of digester. Further, the methods of measuring the gas volume, gas composition, mixing intensity, torque, temperature are discussed in this article. The assembling of 4 liters digester is described which can be operated at various operating parameters which control the anaerobic digestion process. Mixing is very important to enhance efficiency of an anaerobic digester. To attain mixing Maxblend impeller is used in this lab-scale digester due to its better performance for mixing and power consumption. Various design consideration has been described.

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